Rear roll cage

[m3f_TomS2]

I completely agree with you, which is why I'm looking for bolt ins rather than weld in because I'll only be using these when I autox/track the car. I just want more rigidity in the rear during high speed cornering.

I paid $1600 for a custom half-cage when my car was streetable. Only half because I will not drive around on the street with a full cage and no helmet. I care about the contents of my skull. Don't tell me this thing didn't firm up the rear half of the car. To me, $1600 was totally worth it to feel safe while harnessed into my car if it rolls.

[m3f_Solaris99]

In no way am I saying that a half-cage is half-ultimate protection. It's certainly not worthless, though. This is an example of a little hoop behind the driver's head preventing a possible fatality.



https://youtu.be/sYRN70r7Zrc

[m3f_tripitz]

But on a serious note, take a look at most time attack cars in Japan and you'll see the cages are built very thin. You don't really get proper protection unless it's built to FIA standards or close, which many Japanese builders don't adhere to. But since you're talking about a half cage anyway, it's basically just going to be for rollover protection and to act as a harness bar and glorified strut tower bar. You'll need to seriously trim weight to counteract what you'll be adding with the half cage.


IMO go full cage or don't do it at all. You're gonna shell out a small fortune for a NICE custom half cage and it won't really do much for you aside from look cool.

I disagree that a proper half cage does not help. I hit a concrete wall left front and then rear left at an initial speed of 67mph. The main cabin was not damaged at all. I attribute that to a properly installed Kirk Bar, which helped keep the rear of the car caving-in. Also, the harnesses, eat, HANS, and everything else contributing to me losing my car and not having a single bruise/scratch on me. Kind of crazy... So I do think it helps. I do agree full cages for sure are an order of magnitude better.


Most importantly, my race shop and I both believe that it kept the cabin integrity high enough that the doors were able to open and close without issue.

[m3f_englishtom1596q]

I also agree that half cage is better than no cage.

[m3f_tripitz]

Also.. one last thing I would like to point out...



IF you are going to go the safety route, you are basically "ruining" the car. To mount harnesses properly, you are going to have to drill a bunch of holes in the chassis. As I converted my M3 to track use, I kept the interior all nice, etc. At the end of the day, there were a ton of holes in the floor for the 1/2 cage and 6 point harness hooks for driver and passenger.

[m3f_Nate047]

Yea I guess I was thinking more of a roll bar in my mind than a half cage with a proper rear section. That is definitely worth something more in the case of a crash. But don't you think for that much effort you may as well cage the full cabin? That part still doesn't make a lot of sense to me because you've taken the dive into "ruining" the car already, so why not ruin it fully Bottom line I think it's personal taste, and a certain amount of how "showy" you want the car to be vs "because racecar."

[m3f_nholmes]

https://www.bimmerforums.com/forum/s...36-M3-Roll-Bar



He has made a lot of bars, but is far from Japan. You can also try Autopower and Kirk, but some of their models are 3 or 4 piece rather than fully welded and the bar you pictured is fully welded. They may have fully welded options as well. The rear X is also an option in bar design. And bolt in versus weld in is also an option in bar design.



Due to shipping costs for a fully welded bar, you might be best off having one made locally assuming there are shops there that do this work.



The paint is something you can DIY or have powdercoated.

He's shipping mine today, actually.

[m3f_pbonsalb]

I think the Mason Engineering rear strut bar that ties into the rear subframe looks interesting. You have to buy the upper bar and the lower part, so it is expensive -- about as much as a rear roll bar.

[m3f_tripitz]

Yea I guess I was thinking more of a roll bar in my mind than a half cage with a proper rear section. That is definitely worth something more in the case of a crash. But don't you think for that much effort you may as well cage the full cabin? That part still doesn't make a lot of sense to me because you've taken the dive into "ruining" the car already, so why not ruin it fully Bottom line I think it's personal taste, and a certain amount of how "showy" you want the car to be vs "because racecar."

A full cage in my part of the country is a lot of money. My local race shop charges 4k for a very well built and designed cage. That's a lot of money. Since I'm rebuilding my car and have a lot to sort out, this year I'm throwing in a kirk for the events I plan on running while I shake down the car and am running easy. Once the car is running well, I'm putting the cage in next year. I'd rather have some safety this year than no safety. It also saves time with finding the fitment for the seat positions, etc...


This stuff all adds up!

[m3f_englishtom1596q]

The only thing I don't like about the Kirk bolt in cage is that it bolts to the wheel well area. Wish there was a better way to tie into the rear frame rails or rear shock towers like a weld in cage usually does

[m3f_mauromj]

Can someone please PM me Ben's number? I sent him an email about a cage, but never heard back.

[m3f_nholmes]

Sure dude

[m3f_kyrix1st]

I paid $1600 for a custom half-cage when my car was streetable. Only half because I will not drive around on the street with a full cage and no helmet. I care about the contents of my skull. Don't tell me this thing didn't firm up the rear half of the car. To me, $1600 was totally worth it to feel safe while harnessed into my car if it rolls.





Now that my car is full-time track, I could get the cage completed, but I don't know if I'm going to actually race with this. The car can be put back to streetable without too much effort at this point. Fully cage it and I can only sell it as a track car.

Damn, those welds are beautiful.

[m3f_nholmes]

Lots of good info and pics in here, too:


https://www.bimmerforums.com/forum/s...Roll-Bar/page3

[m3f_SQ13]

The only thing I don't like about the Kirk bolt in cage is that it bolts to the wheel well area. Wish there was a better way to tie into the rear frame rails or rear shock towers like a weld in cage usually does

What about something like this? The rear vertical support thing supports the rear seat/seat belts on the E46, so at least it has been tested for rigidity. However, I'm not sure how supportive it would be on the E36. The mounting points have also been reinforced with welded plates. Wheel wells? Fuk that.



IMO the one I have is a good bolt-in solution that isn't invasive (requires cutting, extensive modification to existing parts, etc). For a dedicated track car, welding a half cage at the minimum is the way to go, but since I plan on reverting my E46 back to stock in the future, bolt-in is my only option.